172 [August, 



minute, third joint of antennae very large (at least half as large as the eye) and 

 oval (<J) round and of moderate size ( ? ), arista straight (not wavy), scarcely 

 longer than frons ( $ ) but somewhat longer (?), palpi yellow; wings lightly 

 tinged with yellowish- brown, fringe moderately long, costa barely to middle of 

 wing. 1 about double 2, first thin vein comes off external to the fork at a bend 

 in the thick vein ; legs brownish-yellow, hind femora moderately stout, tibial 

 cilia fairly long and sparse; hypopygium of moderate size, the yellow anal 

 protuberance large, compressed laterally and deeply scooped out at the tip 

 (emarginate),so that the under-side projects in an unusually long lip ; ovipositor 

 long and exserted H mm. emarginata, n. sp. 



23 (22) Halteres clear yellow. Abdomen dusted with grey. 



24 (25) Frons broad {about half as broad again as long) in both sexes. 



<J ? . Thorax and abdomen black, the latter thickly dusted with whitish-grey, 

 causing an almost silvery gleam in some aspects, the former more thinly and 

 with a darker grey ; the anterior scutellar bristle in the male much smaller 

 than the posterior one, sometimes barely more than a strong hair, but of equal 

 size in the female ; frons grey, upper pair of supra-antennal bristles small and 

 under pair minute, antennae rather large (best estimated by comparison with 

 the eye in profile), male palpi small and yellow, with the bristles short, of 

 ordinary size and armature in female ; wings lightly tinged with grey, fringe 

 long, costa to middle of wing ((?) rather beyond ( ? ), 1 nearly twice as long 

 as 2 ; legs light yellowish-brown, hind femora dilated, tibial cilia short and 

 numerous but distinct ; hypopygium large, subanal body rarely, if ever, exposed, 

 anal process large and dusky with the extremity yellow ; ovipositor more or 

 less exserted lj — 2% mm. albicans, n. sp. 



25 (24) Frons narrow (not broader or scarcely broader than long). 



c? ? . Very like preceding species, but smaller and appearing at a different time of 

 the year. Further distinguished by the frons, thorax and abdomen being 

 much more thinly dusted with grey, the antennae only moderately large, by the 

 four small supra-antennal bristles being of nearly equal size, the costa shorter 

 and the tibial cilia longer and less numerous If mm. rata, Coll. ms. 



26 (11) Halteres black. 



27 (32) Meso-pleurse bare. 



28 (29) Palpi (£) very large and almost bare, much like those of nudipalpis. 



$ . Thorax and abdomen black ; frons about one-fourth broader than long, four 



